My MPEG-2 Files Have a Stutter

[marotti]

Hello All

I have a client that uses a laptop computer to play my DVDs and projects the picture for conferences. Using a DVD player would work great for picture quality and playback performance, but he needs to intermix the video with his powerpoint presentations and doesn't want to use two different playback devices, which I can appreciate.

He uses MS Media Player 11 to play the DVD clips and uses the full screen option.

He loads the DVD files onto his HDD so the DVD Drive isn't part of the problem, and to further isolate the symptoms, I provide him with MPEG-2 files so that he isn't using VOB files.

So this problem that I will describe has nothing to do with his DVD Drive on his laptop. Furthermore the problem is also exhibited playing the files on my desktop editing station using MS Media Player 11 (MP) so the problem may be accentuated by the laptop's performance, but is not limited to his laptop.

So I think that it is safe to say that the problem lies with my encoding, or source material.

The problem is that the video plays back fine for a while and then will stop for a millisecond and then continue, which causes a stutter. More about that later.

The first time I noticed the problem I encoded to MPEG-2 from within Premiere CS3 and used high quality (5) and a data rate of 9Mbs. Once I noticed the problem I ran some tests with different encoders and standardized on a Quality Setting of 5 and a CBR of 7.

BTW I ran additional test at varying Quality Settings and CBRs and found that they affected the quality of the video, but not my problem.


In my tests I used my Premiere CS3's MainConcept Encoder, ProCoder Express (Canopus guys told me that my encoder was probably better than their trial version of ProCoder as the codec in my PE is newer), Cleaner XL (uses MainConcept from what I understand), TMPGEnc 4.0 XPress Trial Version, and CCE Basic Trial Version.

They all performed relatively the same, what I have termed a Stuttering, is like the video pauses momentarily and then starts playing a couple of frames or so later. It does that mostly in the same place in the clip, but not all of the time. Sometimes it plays through just fine, but when it does glitch, it's generally in the same place in the clip.

I checked out the source footage and it is clean. It isn't a complicated clip, a customer at the front counter gets her meal and turns and walks away. As she turns to walk away there is a stutter and after she walks a couple of feet there is another stutter at times.

I was using some knee, pedestal and gama settings in the camera, but other than that I was just shooting at 60i and 1\60th shutter speed.

Are their any other settings that I could tweak (Profile, Level, Mframes-Nframes, Closed GOP, Automatic GOP, Macroblock Quantization, VBV Buffer Size, Write SDE, Ignore Frame Interval, Reaction Parameter, Initial Average Activity, Minimum Frame Percentage, Pad Frame Percentage) or any other settings or ideas??

I already tried every combination of Quality and CBR setting, and they don't seam to make a difference on this effect.

Please help if you can, this is driving me nuts

You guys have already been very helpful in the past, so thanks in advance!!

AM

[Soopafresh]

Hard to say without a short video clip of the problem. It could be the way the audio and vid are muxed together, it could be the mpeg2 decoder, it could be TFF/BFF dominance.

Try playing it with VLC player, as this will rule out your mpeg2 decoder. If it still stutters, cut a 10-20 second clip and post it somewhere where we can take a look.

[lordsmurf]

TFF/BFF dominance means your interlace fields (top or bottom) are backwards in the encoder. Flip it.

[marotti]

Hey Guys... Happy Thanksgiving!

I have used all of the players of any popularity including the VLC player, with similar results, so it doesn't seem to be a player specific issue.

I tried flipping fields and every other setting that the encoder had to offer, also with no change in results.

So I am horrified that it might be caused by my source video!

When playing the tape back there isn't any indication of the stuttering, it plays just fine (source footage, unedited or captured).

I used a Canon XL2 for the footage and in the settings the DP changed the knee, pedistal, and increased the color saturation. He also shot it at a +18 Gain. We were converting to B&W and trying to simulate a security cxamera as an end result, so we wanted to degrade the image... but we didn't want any stuttering.

I have included a link to some test footage. It contains 2 shots of the same sceen, the first is color corrected to the pre-B&W conversion and the second is the raw captured footage as it was shot. I wanted to see if any filters or processing in the NLE might have added the problem.

So please give it a look and tell me what you think... Thanks!

BTW the extention is .exe so that when you go to the link it will initiate a download. Once downloaded, just change the .exe to .avi and it will run.

Thanks Again!


http://www.iti-now.com/plsdl/Security_Chapter-1_Filtered-Unfiltered.exe

[Soopafresh]

Your source video looks like regular DV video, which is BFF. Just save yourself the trouble and deinterlace your footage and encode progressive.

deint.mpg

[marotti]

Hey Soopafresh,

A couple of points.

First of all, the file that you provided wouldn't play in MS Media Player (MP) correctly, but did play in VLC just fine. My client uses MP, but if I found a solution, I could probably get them to all use VLC.

Q1) How did you deinterlace and encode progressive?

Q2) did you see the problem running my AVI file?

The AVI file stutters, so it isn't my encoder, but rather the source file probably.
It might run OK the first time through, but if you loop it, by the 5th playthrough it usually stutters somewhere between the time the girl turns to leave the counter and when she is finally off camera. It always happens there and the file you posted ends before that.

Could you loop it and play it for a while so that I can see if the problem happens to you?

Thanks a LOT !!

I appreciate all of your help

[Soopafresh]

If it stutters the 5th time through, it's almost certainly the speed of your CPU or your video card. Turn off your Virus checking software while you're playing your files back. Encode at a lower bitrate - try 5500K for Mpeg2


To Deinterlace and Encode Progressive:

Using TmpgencXpress: (The Green Highlights are Important)

1) Load file, ensure it shows it recognized the file as having BFF



2) Deinterlace with the following settings



3) Ensure Mpeg2 encoding is Progressive